Thinking of taking on a fun project of sandblasting the trailer and also repainting it. Anyone familiar with sandblasting and the equipment needed? What would I need and how much would it cost? Or is it better off paying someone else the $$ for their time and mess?

I'd pay somebody for a trailer. Don't foget, you need to flip it over. You also need to get into the cracks for the shackles, etc. It's easy to ignore them and paint over, but that's where the rust will breed. Also consider that there is absolutly no rust protection inside the tube. If the outside looks crusty, imagine what the inside looks like!

If you have more time than money, the little portable blasters will work. I think (guess) they will draw around 15-20 cfm. That's more than most home compressors are capable of sustaining. You'd be better off renting a very serious gas powered compressore and blaster. Even the smallest gas powered compressor will be putting out close to 1,000cfm. Now you can get the job done in a couple of hours instead of days.

How much is it worth to have it blasted? I remember a guy telling me $250....fair price?

I have car chassis blasted ... costs me about 125.00..but it's the only way to fly if you want it clean... you have to disassemble the entire thing and get it over to the blaster... be prepared to prime it right away.. it will be orange in one afternoon. I think a large boat trailer would cost about 200 to 250.00... Don't even attempt to do any blasting with a small blaster... you will spend more money in electricity.. let alone the time.. than if you just bite the bullet and have it done.

a boat trailer 25-30' minimum 500.00

I have 2 blast hoses running 8 hours a day. Going rate for whiteblast is around $.50 a square foot.

whats the minimum charge????

Brother had his blasted and primered for $150. For a 23' boat. It takes a comercial compressor to supply the volume of air needed for this. You will only get a minute or so of blasting, then have to wait until the compressor can build back up if using your standard home owner compressor.
You will also be picking sand out of every nook and crany in your body unless you have a full suit with head gear. It just ain't worth it when it can be done by someone who has the equipment. Not to mention something along the lines of a hoist to flip the trailer over.

We don't really have one, but most of the stuff we blast is huge. Just make sure they protect your bearings, and don't get the blast job wet or oily.

white blast as in sp 10? dam thats real cheap